1. Field of the Invention
The present invention relates to a capacitance-sensing vibratory gyro and a method for detecting changes in a capacitance.
2. Description of the Related Art
In general, in the case where a vibratory gyro is used as a sensor for detecting a camera vibration or shaking during hand-held shooting or a position of a motor vehicle by an angular velocity, an analog output signal from the sensor is converted into a digital signal by an A/D converter and then a predetermined correction process is carried out based on the signal.
In this case, in an A/D converter with a voltage comparator, since the reference voltage level for the conversion sometimes depends on a power supply voltage level, detection sensitivity of the sensor must depend on the power supply voltage level to improve the detection accuracy.
For this purpose, in a known art, the amplitude of the signal for driving a vibrator, which is a sensor, is varied depending on the power supply voltage level, thereby changing the output level of the sense signal from the vibrator. As a result, the detection sensitivity of the sensor depends on the power supply voltage level to improve the detection accuracy (refer to, for example, Japanese Unexamined Patent Application Publication No. 11-44540, in particular, pages 1 to 3 and FIG. 1).
Unfortunately, in the known art as disclosed in the above-described patent document, during a time period from applying a driving signal dependent upon the power supply voltage to the vibrator to receiving a required sense signal from the vibrator, many conversions, electrical to mechanical and vice versa, are required. These conversions accumulate conversion errors such that sufficient accuracy to precisely follow the change of the power supply voltage level cannot be obtained.